Chucks are employed for grasping and rotating a workpiece in a metalworking or woodworking machine. All chucks have limitations. Chucks may not be rotated at such a speed as will cause the chuck jaws to move radially away from the rotational axis, thereby so weakening the grip on the workpiece as to permit the same to come loose and fly dangerously from the machine. Recently a proliferation of machines, having high spindle speeds, high power, and very tough cutting tools of ceramic and the like, has exacerbated the aforementioned.
Generally, the attempted solution to the problem has been to attach complex counterweight mechanisms to the chuck jaws. Generally, the counterweights have moved away from the rotational axis, thereby attempting to stabilize or balance the jaws such that a firm grip on the workpiece is maintained at higher rotational speeds. The structures employed have been cumbersome, costly, and only partially effective, for a limited range of speeds.
Another attempted solution to the problem has been to increase the force actuating the chuck jaws prior to turning the workpiece, thereby increasing resistance to radial movement by the chuck jaws away from the rotational axis. A disadvantage of this is undesirable crimping or bending of portions of the workpiece.